Pachycephalosaurus

- Pronunciation: pak-ee-SEF-uh-lo-SAWR-us
- Translation: Thick-headed Lizard
- Order: Ornithischia
- Suborder: Marginocephalia
- Infraorder: Pachycephalosauria
- Family: Pachycephalosauridae
- Height: 10 feet (3.1 meters)
- Weight: 4,000 pounds (1,814 kg)
- Length: 18 feet (5.5 meters)
- Period: Late Cretaceous
- Description: Herbivore, Bipedal
- Notes: Wart-like knobs and five-inch (13-cm) spikes fringed theten-inch (25-cm) thick dome of Pachycephalosaurus, a rare dinosaurfirst discovered in Montana. It had a narrow face with leaf-shapedteeth and in all other respects it was like other ornithopods-- two-legged plant eaters with five-fingered hands, three-toedfeet, and a long, heavy tail. Largest and last of the "bone-head"family, it and all its plant-eating relatives and carnivorous cousins became extinct 66 million years ago.